As the industry pushes for more productive cows, the reproductive performance on farms declines. Poor reproductive management on farms can be costly due to decreased milk production in late lactation, higher feed costs from a longer calving interval, and more labor and supplies from multiple breedings. To investigate techniques to improve the reproductive efficiency on dairy farms, two experiments were conducted involving Holstein heifers of breeding age and early postpartum Holstein cows.
To investigate tail paint utilization and potential relationships among behaviors and activity, eighteen Holstein heifers were randomly assigned to one of three treatments: control (CON), tail chalk; treatment-A (TRTA), tail chalk with proprietary ingredient; and treatment-B (SPRAY), spray formulation. Experimental design was a replicated 3x3 Latin square with 6 total squares, 3 animals per square, and 3 periods of 14 d each. Visual observations were performed for thirteen behaviors in 30 min segments every 2 h from 6 AM to 6 PM. A synchronization protocol starting on d 1 of each period (Ovsynch®: 100mg GnRH at d 1, 25mg PGF2α at d 7, and 48 h later an application of 100mg of GnRH) was used to stimulate periods of high and low interactions. Ovaries were examined via ultrasound imaging on d 1, 8, and 10 of each period. Statistical analyses were performed using the GLIMMIX and MIXED procedures of SAS (v9.4). Heifers receiving SPRAY had lower number of licks received per day (P < 0.001) and lower tail paint removed regardless of day or follicle size (P < 0.01) when compared with CON or TRTA. Rump lick received (P < 0.01), chin rest received (P < 0.01), anogenital sniff received (P = 0.02), mount received (P < 0.01), and both initiated and received behaviors for attempt to mount (P < 0.03) occurred more in heifers with large follicles on d 8 and d 10. Dairy operations that have problems with tail paint removal and false-positives may benefit from changing to a tail paint product with a different consistency, such as a spray formulation. Producers looking for heifers to breed should focus on those receiving rump lick, chin resting, anogenital sniff, mount, and attempt to mount, or increases in daily activity.
Next we examined the effects of rumen-protected methionine or choline supplementation on uterine health. Seventy-two Holstein cows were fed the same TMR and randomly assigned to four treatments from calving to 30 DIM. Treatments were: CON (n = 16, fed TMR with a Lys:Met = 3.5:1), MET (n = 20, TMR + Smartamine M® to a Lys:Met = 2.9:1), CHO (n = 16, TMR + 60 g/d Reashure®), and MIX (n = 19; TMR Smartamine M® to a Lys:Met = 2.9:1 and 60 g/d Reashure®). Starting at d 31 cows were randomly re-assigned to two treatments: (CON; n = 36, TMR with a Lys:Met = 3.4:1) or (MET; n = 36, TMR + Smartamine M® to a Lys:Met = 2.9:1). Cows were evaluated at 4, 7, 10, 13, 15, 17, and 30 d after calving for the presence of secretion using the Metricheck® device. Contents were scored at 0, 1, 2, or 3 and smell was scored at 0 or 3. On 15, 30, and 72 d after calving, the uterine endometrium of all cows was sampled using a cytological brush and streaked onto slides. Each slide was counted by one person for the presence of polymorphonuclear neutrophils (PMN). Statistical analysis was performed using the MIXED procedure of SAS. On d 30, a treatment difference was detected using the metricheck score and smell (P < 0.04), with treatment MIX (0.38) having a lower score than CHO (2.11). In conclusion, supplementing cows with rumen-protected methionine may have a beneficial effect on cows’ uterine health. The use and combination of techniques in this thesis may improve reproductive performance across dairy farms and have a huge impact in profitability.